Have any of you had bad muscle pain with folfox chemo treamtment?

I had my third round of chemo 6 days ago and yesterday I started to have pain in my stomach muscles and back when I cough, I have been having this dry cough since the first round of chemo, but last night I couldn't sit without pain on my lower back, the pain got really intense when leaning back, like a horrendous pain that I hadn't experienced yet. I took some tylenol and it lessen the pain a whole lot. I contacted the oncologist and she said that if Tylenol was helping then the pain is muscular/skeletal and it shouldn't be worrisome unless it gets worse or other symptoms arise.

Has anyone of you experienced this? What would cause muscle pain like that?

Update:

It ended up being a blood cloth on my lung! the 4th day the pain was untolerable so we went to the ER and after scans they did find the blood cloth. No surgeries neeed, just blood thinners for the next few months.