cat causing trauma to genitals

my cat keeps irritating his genital area until it gets infected...he recently got out of the hospital on an 11 day stay where he almost died because he caused so much damage he got blocked..he was fine now hes doing in again...he has undescended testicles, could this be the cause

Did he get blocked because of crystals rather than damage?  If he had crystals that could be the reason for this behavior and they need to be treated.  I would imagine that the testicles could also be causing this.  Is there some reason why they haven't been removed?  I know it is a more involved surgery, along the same lines as a spay in a female, but usually they are removed.

Excessive licking is often a sign of UTI or allergies. What did your vet have to think about the issue? Was a urine sample/culture done?

Also, if he had to be catheterized during this recent blockage, he may still have some associated pain. Is he currently on any medications...antibiotic and/or pain?

To keep him from licking, he'll need to wear an e-collar while he heals and the underlying cause is addressed.

he was catherized yes but hes been home over a month now and was totally improved, but this started last week and I cannot get him to the vet until next week...i put him back on the anibiotics he has taken for 14 days but I still had plenty left (thank goodness) ive been bathing him everynight and putting hydrocortizone cream and neosporin on the nightly as a temp version of resortin which helped the last time..i am getting him an ecollar today ..he isnt fixed bc hes disabled and honestly ive been scared to trust any one. but im planning in getting it done this month...no crystals were found in his urine they tested it daily bc they had to check his levels daily....he is hurting though is there anything i can give him to help ease the pain

There are no safe OTC pain meds for cats. You would need to get meds or a prescription from your vet.

Also, be careful when using antibiotics without a known infection. This can lead to antibiotic-resistant infections (the same thing can happen if you do not use an antibiotic for the duration needed.)