Help: painful swelling, then weeping/raw wet skin. A crust then forms before it heals. Moves from place to place. Started after dirty public shower?

See dermatologist. There a number of possibilities but this is not treatable with otc meds.It is likely a bacterial infection , that requires systemic antibiotics. There also autoimmune conditions such as pemphigoid, this requires examination, probable biopsy and appropriate systemic medications.
Skin condition. Hard to diagnose this without seeing it, but it could be a fungal infection. Easily treatable with otc meds.