Siamese male swollen Prepuce

I have a 3 yr old Siamese male. 10 days ago we noticed excessive licking in penis area. He has a swollen prepuce. We took him to our vet who gave him prednisone and an antibiotic. Ten days later very little improvement. Been wearing an elizabeth collar the entire time however we noticed his brother cat has been licking him once in a while. They are very close brothers. Always groom each other. We think hes going to that area because his brother is leading him there by spreading legs. Last three nights we separate them over night and literally watch their every move during the day. This is exhausting We need help Also, never has there been excessive licking or any issues in this area. We think maybe he had a cut or something that started this. Vet checked his urine and very little to no bacteria  no crystal issues      

top pic was original infection   second pic a few days ago  

Hello - I am concerned that this cat may 'block' - lose the ability to pass urine - which can be a life threatening emergency, so please be very alert for a reduction in urination and if observed, contact your (or the emergency) vet.  There are articles about 'blocked' bladders and cystitis, which can lead to kidney failure, in our blog.   In my experience, infection is rarely the cause of urethral blockages and I am very concerned that further investigation may be needed as a matter of urgency.  Excessive licking implies pain.  Please therefore call your vet for triage.

Although he's been going to the bathroom less frequently, he's been peeing a good amount and pooping  - the meds he was on we think led to less drinking of water and food in general.  Like I said my vet tested the urine and didnt think it was a bladder issue - urine sample looked good.

Hi - at a guess, it could be an issue causing a narrowing at the end of the penis or a lump or mass in the shaft.  I cant really see the lump in the second picture.  If the wee-tube going through that place becomes squashed by whatever it is, then the risk is that the outflow of the penis could become obstructed, leading to a 'blocked' cat and which can lead to kidney failure, no matter where in the tract that blockage occurs or what the cause is.   It sounds as though your vet ruled out immediate / imminent blockage, but it seems unlikely that they left it there.  Do they have a plan to identify and thereby consider treatment for that swelling?   Has hair caught encircling the tip of the penis been ruled out?   Because of the urgency involved if the tube were to become blocked, it sounds as though further investigation would be merited.   Good questions for your vet are:  what COULD this be?   How severe is each option?  What do we need to do in order to distinguish between these options and what do we need to do in order to look after my boy while we find this out?  Your vet will have better information than me having examined the cat, but i would predict that there may be a few unknowns requiring anaesthesia or closer examination for diagnosis.