Poor boy!
He looks like he has a sinus infection - his nares are clogged with something, dried pus or mucus?
I can't give you medication advice, but if you search here you may find some; I'm sure an experienced peaperson will show up soon to let you know what would be effective. In the meantime, you might see if you can gently clear his nares so he can breathe better.
Why did you force feed him, how long has it been since he has eaten or drank water by himself?
I don't have experience with this myself, but I believe that it was our super-duper-pea health expert @casportpony who recommended looking inside the beak at the roof of the mouth. SOmetimes you can see further evidence of pus clogging the sinuses there. Post a picture if you can.