Now I'm really meddling.
I know people say you should avoid religion and politics in conversation, but I think "eating habits" might be even more controversial. Tell me my favorite political candidate is bunk, and I maybe expected someone to disagree with me. Tell me I'm eating poorly... Hey now, that's personal!
All I want to do with this post is to simply offer you a challenge: Starting today, eat half as much sugar as you normally did previously. Cut the number of sweet things you consume in half, and unless you're on vacation, round down.
After 3 weeks, if you don't feel better, eat whatever sugar you want. If you do feel better, cut your sugar intake in half again.
I can tell a noticeable difference in "how I feel" when I have less sugar (or more sugar.) Maybe the same will be true for you.