I think I have an idea.
The fecal came back clean, but the vet said there were pieces of undigested food and it's due to the temp being too low. His basking temp were 104-110F!
I've been off for 2 days now and I had a chance to watch him, I think might I know whats the problem!
This runny poo business started since I got a new thermostat. His basking temp used to be around 95-97F and he was fine. Since the new thermostat and the rise in his basking temp he doesn't sit directly under the lamp anymore. He sits on the side of the platform where he probably doesn't get enough heat. He is always gaping when trying to bask.
I've decreased the temperature to 95.. will see how it goes
being weighting him every day now, he keeps putting on weight
I can't take a picture at the moment, my phone is being repaired. Only have pics from 10 days ago