What kind of rash is this? 23, f, 150lbs

23 female 150 lbs. no daily medicine, no known allergies, no known under lying medical conditions.

About two weeks ago I noticed my armpit started to itch. It wasn’t too bad so I didn’t think anything of it. A couple days go by and I’m itching both of my armpits constantly and I’m now breaking the skin. I assumed it was from my deodorant because I bought a new kind. Chalked it up to an allergic reaction and did my best to get rid of it. Nothing I did helped. I went to the doctors and said I think I’m having an allergic reaction to something. they told me they think it’s an infection, take antibiotics (cephalexin) for a week and it will clear up. About 3 days into the Medicine I noticed the rash has now spread to my stomach/chest, behind my knees/elbows and v line area. (Can’t show those pics but they look identical to arm rash) so I changed my laundry detergent to safe one, changed my body wash, started taking allergy medicine daily, using hydrocortisone for the itching. Did all of that and I have no relief. I’m not sure if it’s an allergic reaction at this point. My body is so itchy and nothing is giving me relief. I’m itching my skin open and end up causing myself more problems.

I noticed I have a rash the same spots lymph nodes are.

Pictures- https://imgur.com/a/JLZOYx0