So sorry, he really should see a vet, is there any way a friend or family could lend you money to pay for it?
I would weigh your piggie everyday at the same time, record the weight and you should after a few days see a trend. If it’s a downward trend then you know he is losing weight and needs support feeding with mushed up pellets or critical care. You should be able to buy syringes (without the needle) at a pharmacy. It’s then a balancing act if he needs just a top ups a day or more support. You should be able to see this by weight changes. It should like he has an infection or trauma where his front teeth may have broken under the gum and that’s what is causing them to wobble. in that case they will drop out and you should then see new tooth growth break through the gums in a week or so
If in the other hand his weight is stable then he is eating enough food, make sure he is getting lots of hay as that should be 75% of his diet