Where should I report food poisoning that may have occurred at a Mcdonalds in Chiang Mai? It's probably bacterial but may have been chemical food poisoning, not sure.

Backstory for anyone interested:

I ate at a Mcdonalds in Chiang Mai (the one across from Tha Pae Gate) and had a double big mac and a coke. Well I didn't notice anything wrong with the meal until a few minutes after I finished, when there was this really bad aftertaste in my mouth. I can't describe how it tasted but it was foamy and in the back of my throat. Anyways I didn''t think too much of it until about 20 minutes later when I started feeling nausea while walking home. I felt like I was going to throw up but didn't, just threw up air. Anyways, I've been sick for two days now, not too bad as I haven't thrown up. But I suspect either there were chemicals in the food or the coke, or it was sitting out too long before they served it to me because it wasn't very hot and they had it ready within less than 2 minutes after I ordered it. It's not so severe yet that I feel I have to go to the hospital and waste money, as I'm waiting for it to pass, but I thought if it was a chemical in there then it should be reported. Reason why I suspect a chemical is because of the foaming in my throat and the aftertaste, as well as how fast it caused me to get sick. I've read the usual incubation time for typical food poisoning from bacteria takes at least 6 hours most of the time. I've never tasted any burger or drink that had an aftertaste like that either so that's why I'm sure that my illness came from that specific meal and not one from the day before or anything.

There are types of food poisoning that have an almost immediate effect.

You can report this to the local Ministry of Public Health office but unless they receive a rash of complaints (at least dozens if not hundreds of cases) they are going to shrug it off.

Ok thanks Sheryl, I'll give it a try.