your gyn isn't the best provider to follow up on this with.
many viral infections that are non-std related also cause these symptoms. at this point you can seek out oral std testing from your local std clinic if you need the peace of mind. otherwise if symptoms aren't gone in 2 weeks, see your provider again.
I've had white patches on my tonsils before, and had a sore throat at the same time. It was just tonsillitis and it went away within a week or two. Tonsillitis can appear rather quickly, and is easily treated. It's non-STD related. You can go and get oral STD checking for your own peace of mind, but I'm sure you'll be ok. I highly doubt it's "food debris.". That doctor seems to not know what they're talking about. If you're not better within a couple weeks, make an appointment with your family doctor, and demand testing or figuring out what's wrong with your throat.
Sore bumps have appeared on the back of my tongue now. I'm going to see another doctor Thursday, I hope they give me a better answer than "your tonsils are naturally large and will always have these white patches, it's food debris". Can't stand another minute of this wondering!