Welcome to JustAnswer! I am a licensed veterinarian and would be glad to help!
Did the veterinarian evaluate closely the prepuce (the sheath around the penis) and the penis itself on examination?
Was a urine sample tested?
Yes, it was slightly swollen but now seems to be back to normal.
He is getting urine and blood tests done now but there don't seem to be any signs of UTI - he's pooing and peeing fine.
I would make sure the prepuce itself is well examined and even flushed out in case there is something foreign and irritating hiding in the sheath.
They kept him overnight and did say they examined it carefully. Not sure if they flushed it. He isn't biting the penis itself - just the skin around it.
By around it I mean the skin on his stomach on either side.
It is difficult to say if there is an allergic reaction that can cause this or pain, but those would be the 2 more common causes for biting of the area/
Would this also result in lethargy and not recognizing and responding to anyone when we walk up to him?
Yes - it easily can.
The question would be - if pain,what from?
- The skin itself having an infection?- The bladder or belly pain?
Could it be something internal?
(yes - see above)
The skin itself looks OK. He's even been on antibiotics for three days now.
Its as if he's trying to bite/lick the skin on his stomach to fix something that's inside.
X-ray didnt show anything.
You may wish then to consider an ultrasound
To get a better look inside - as a non-invasive test.
OK - I'll check with the vet on that. Could it find something the x-ray missed?
But from the symptoms would you say it is more likely to be an obstruction or allergy of some sort and not an internal infection?
An obstruction would be unlikely
Normal urination, no vomiting, etc
Some type of infection or allergy more likely
What are you suspecting that the ultra-sound might find?
Any time of infection or irritation internally
OK, Thanks. Any other suggestions?
Without an examination it is hard to make more specific recommendations than what is discussed above, especially if the x-ray, bloodwork, and urine are negative.