I throw up durring or after nearly every sports practice I go to, should I see a doctor or take supplements?

I am a rower and during our winter season we are inside erging 2 or 3 days a week but after or during almost every practice I throw up whatever I ate for lunch that day. I'm not really trying to figure out why (although that may be what I should be focusing on) but instead I was wondering if I should see a doctor or just be taking supplements for what I'm not taking in every day (or both)?