Kristen it sucks. And I know things are brutal but try to plug through without the breaks if you can. I lost the hair too... Had a LOVELY bald below the ears thing happening and it actually thinned out up to my crown on my tumor side... Not pretty but i used a scrunchy to pull my hair back into a ponytail/bun it had all of maybe 3 hairs in it but I lived like that for three months post treatment - by that time I had 1.5 inch sprouts and had extensions put I for about 6 months - then took them out and had a bob. I also used those colorful yoga headbands it didn't look amazing but it was ok.
As for pain and mouth sores, I rinsed, I carefully cleaned my mouth after every meal / drink - and I used manuka honey - it helped with the sores. I was very blessed in that I was able to tolerate the pain.

Hugs girl you will get through this - push yourself. And use your pain meds if they help, I couldn't use my peg so I chugged ensure several times a day - not fun but it worked.