I want to ask for a raise, position change, or modifications to workload and have no idea how to go about it

So I have been transporting patients for over a year now. This isn't a long time at all in the workplace, but I have circumstances that I feel warrent this conversation. I started out working as a patient transporter for the entire radiology unit. doing this job meant moving patients and doing paperwork like sending images to different hospitals. This position I was moving like 1-3 patients an hour while taking turned with 3 other people. A few months ago I was offered a newly created position where I only transport for CT and dont do any paperwork. Plus I go from 8 hour to 10 hour shifts and have the same pay. I thought this was a good deal and offered to switch. This is a brand new position so we are still kind of in the finding out phase on what my duties should be. For example: at first it included checking patient information and seeing if the correct IV is in place, but eventually I was told I shouldn't worry about that since Im not properly educated on IVs.

I have been struggling to keep up with the amount of patients I am required to transport at this new position. The number has quintupled and I practically never get a chance to sit down until lunch. I thought that I would get used to it after a while but I am slowly getting more and more burnt out from the amount of movement per day I have to do. I average walking about 10 miles every day pushing beds and wheelchairs. My feet are swolen and painful when I get home (I wear expensive running shoes and compression socks). It's so bad that some days I wear a knee brace because my tendons can't handle the constant daily stress. Same with the pushing and pulling on my wrists from the beds. Most of these patients are from the ER, but I have to grab in-patients too.

The CT techs use to grab all of the ER patients and would switch off with each other to make the load easier but since I was transferred here I grab almost all of them. I keep passing the other transporters and seeing them sitting down on their phones relaxing and can't help but grieve the position I used to have. I want to ask my boss to transfer me back but none of the other transporters would ever be dumb enough to switch with me. I can't keep going on like this. On top of everything some of the CT techs treat me like crap. I dont know why one in particular doesnt like me but she is always watching me and waiting for me to do something wrong so she can aggressively criticize me for it. An example would be me asking for a coworker to lock the bed and she yelled at me to say please and made me apologize in front of everyone to embarrass me. Another time I pumped to bed up too fast and she yelled at me to the point I started to cry and she acused me of not caring about the patients. She tells me to go home early during these incidents and It makes me feel like trash.

To be honest I feel like Im getting bullied, but when I bring it up to my boss he sides with her. Saying if I was doing something wrong then shouldn't I want her to let me know. Maybe some are valid criticisms but I still feel targeted. Im the only person she does this to.

Regardless, I am getting so tired of this job and I feel it is unsustainable at this rate. I want to go back to my old position, but I doubt that would happen. I want to ask for a raise to match the increased workload and I also need to have some modifications added. One mod I need specifically is to have the other transporters grab the in-patients. They already do this for the rest of the department and USED to do it before this position was created. Another would be that it needs to be expressed that I do not grab every patient. The CT techs still need to help. (This was told to me when I was hired and it seems some CT techs dont know or think I am making it up to be lazy)

I really need some advice on how to go forward. Im 21 and still new to the workforce. I feel like Im going to get some comments about how Im asking too much or being entitled and I have the perfect job. I really just dont know and need some perspective I guess.