I’m not supposed to go to work, but can I still teach my 2 hour night class?

I’m in Japan teaching English. I REALLY think I got food poisoning. I was throwing up, spewing out both ends last night and I think it was from the chicken I ate. :/ I went to the doctor here last night, but since I can barely speak Japanese, communication didn’t happen very well. He said it’s a stomach virus even though i tried to explain i think it’s food poisoning, and he told me come back again today. So, I went back today and he said don’t go to work today or tomorrow. well, i teach English at jr high schools, but school is out for them, so since school is not in session, we have to just go to the board of education office and just sit there and study Japanese. I guess the doctor talked to my boss and said why dont i just take a sick day today and tomorrow. Thing is, is now I feel fine. I think it passed. I teach an adult English class on Wednesday nights, and it’s noon now, and I think I’ll be fine to teach the 2 hour class (that I already had plans for!). What if my boss finds out that I am working tonight, and not resting??? The adult English class and my main full time job are separate. Am I just being crazy? I forgot to ask the doctor, and honestly to ask him would have been difficult. We had to use my electronic dictionary a lot. Or should I just rest? I honestly feel fine, and haven’t had any stomach trouble at all today. It seems to have stopped last night. It’s such a HASSLE to cancel the class and I had to cancel the last time it was my turn when I was REALLY sick (about a month ago—i had a bad cold). What should I do?? Any advice? Any medical advise, or even Japanese culture advice would be greatly appreciated, thanks.