Rashes Appeared Under Armpit And Have Swollen Lymph Glands. Could It Be Hives?
From your clinical description & history, it does seem to be some sort of an allergic phenomenon & not hives per se.
Please use a topical cream containing betamethasone & miconazole & apply it twice a day for 3-5 days together with a once daily oral non-sedative antihistamine of the fexofenadine180mg group for the same duration. You should find it clearing by then. If not, then its time to visit a dermatologist for further evaluation as we may be missing things online that a dermatologist in person would be better placed to opine on & perhaps may request a skin biopsy et al.
I wouldnt worry too much about it currently but there are some inflammatory skin conditions that mimic an eczema & need to be thought of after 5 days of a trial with aforementioned medications that your local pharmacist should be able to supply you with.
Cheers & Godspeed!
Dr Praveen Rodrigues MD