Hi S.,
I think your son has a stomach virus in addition to his cutting teeth. That amount of diarrhea and it going on for a week is a little too much and little too long to contribute it to the teething. Maybe when you went to see your Pediatrician it hadn't been going on for as long or had just started and that is why he thought they might be related.
As for the diarrhea, you need to try to get something in him besides just liquids. Liquids in = liquids out. Pedialyte is excellent for keeping him hydrated and if he is taking that well, keep offering it but try to also offer other foods like the BRATY diet. B=bananas, R=rice cereal, A=applesauce, T=toast and Y=Yogurt. Look for yogurt w/ Live Active Cultures. Also, if he is taking a bottle, try switching him to Isomil DF (soy based formula DF = diarrhea formula). Babies will sometimes become intolerant to regular formula with diarrhea and so giving the soy based formula for 5-7 days sometimes helps. If your son is still having a lot of vomiting, I would recommend you get him re-evaluated b/c then it is harder to offer solids as they will keep coming back up. The main thing is to keep him hydrated, so please continue the pedialyte but again try to get him to take the formula or BRATY diet also.
I hope he gets better soon!