Hi I can only say maybe to confine him more to a smaller area of the house and maybe get him out more than the 4 times a day. Maybe he cant hold it as long.
We are in the midst of training our pups one 4 month and the other 5&1/2 months and one doing well but the other has seemed to regress and is now peeing where ever in the kitchen where they are gated in. Was going on pee pads in the kitchen and outside but now will pee right in front of me on the wall or under the table.
The other one is doing pretty good.
Also starting to experience allergy issue as well.
Sorry cant give more advice.