I agree your rash is most likely fungal--sounds like ring worm a sort of
fungus-- try washing and thoroughly drying area twice a day and apply
Clotrimazole cream (lotrimin AF) twice a day followed by a pure cornstarch
based baby powder to keep area dry.   Keeping the area dry is the key to
fighting a fungus infection and pure cornstarch powders will work better
than talcum powders.

Regarding the urinary tract/bladder infection--if the infection didn't go
away the first time you were on the erythromycin, then it must be resistant
to it--- never let a urinary tract infection wait--- i could turn into  a
very sever kidney infection called pylonephritis and require more treatment
than just going to md or er in the first place----- See your md they will
most likely get a urine sample-- run it through the lab, and prescribe some
emperic therapy like what was previously mentioned-- cipro etc...

Also with any fungus skin infection you should always treat for a week or 2
after symptoms are gone to ensure total clearing of the fungal infection.

Hope all goes well.

Joe -- Mass Rph

20% of E. coli is resistant to Septra, however it is still useful in
patients who have not had prior treatment with Septra, and is
considered the drug of choice by many urologists.