Single parent and out of PTO. What are my options?

So, I'm a single father of a 3, almost 4 year old. I was previously a stay-at-home father, when my wife suddenly passed away in December last year. I took a short time to come to grips with things, but ultimately had to get my son in daycare and get back to work full-time.

I was able to get back to work relatively quickly(back in March) at a former employer with a schedule that worked well for me. I was very honest with my employer about my situation, so they're fully aware that I am now a single parent, and they were very understanding at the time.

Unfortunately, with it being "sick season" and my son being new to daycare, he ended up sick a bunch. So, everytime he was sick, I would have to keep him home and my job is not a job that can be done remotely. I have literally taken NO days off, other than for my son being sick and myself(and only if I was really unable to work).

I knew fully well that my PTO was coming close to running out and that it won't reset until March. So, I started planning with family members for days ahead that his daycare would be closed and I would need to work. The only day that I wouldn't be able to find coverage for was this coming Monday, so I requested it off with my PTO.

Well, this week my son comes down with some bad cold, has fevers for 3 days straight and I had to keep him home everyday except Friday. I took him to the doctor and even got a note from them just to cover myself however I could.

He was able to return to daycare Friday and I was able to return to work. My manager had previously messaged me on Wednesday to let me know that they tried to put PTO time in for me and it was denied due to the fact that I had no more time left to utilize. I responded that unpaid time was fine if it had to be, because I did not have any other option. However, when I was at work Friday my manager mentioned that they would have to speak with their manager and HR to discuss options. They previously asked if I still planned to be out this coming Monday too, which I responded that I would try to find a child care solution, however I was previously unable hence the request to use my PTO. They told me Friday that technically, that PTO wouldn't be available because it should have been used for the days I was out this week.

I responded again, it's fine to use it whatever days, it doesn't change the fact that my son was sick and had to stay home and that daycare would be closed Monday, so again he would need to stay home. I just couldn't shake the feeling of anxiety and concern over seemingly a small issue as a day or two being unpaid. There was coverage at my job. I feel bad enough taking all of this time and being unavailable to help my coworkers. I just can't help but feel like I should be doing something to protect myself in case this becomes a bigger deal. My manager says they're supposed to meet with HR Tuesday and discuss this. I'm not sure if this is just normal protocol and I'm overthinking things. I was even able to find childcare for Monday so that I could work.

This whole situation was unfortunately just the perfect storm of events which I explained to manager. All of my family members were unavailable to assist me this Monday and with my son being sick. I can't really expose other people to my son's illness beyond the fact that I just want to be there to care for him.

I spoke with my psychiatrist about this all and they mentioned applying for unpaid FMLA as an extra layer of protection, but I wasn't really sure I understood how that could be used either with short term notice, or just for periods of time that were not predetermined.

Now, to make my anxiety over everything worse, I am feeling sick myself. I can only hope that I don't end up as bad as my son. In the meantime, I guess I just needed to rant a bit, but also I was hoping to see if anyone had any advice of what I can or should do in this situation. Thanks!