My story presents similarities with yours. 9 years ago, I came back from Yucatan ridden with parasites: Blastocystis Hominis + Giardia. I took Flagyl for ten days; apparently no reactions but shortly afterwards, I fell sick with multiples food sensitivities, depression, panic attacks, nasal drip, acne, etc. I was also under heavy stress at the time and since I had no access to internet yet--and did not know anything about candida. The doctors never mentioned this possibility.
Could it be the Flagyl -plus the stress-- that caused the problem?
I did not follow a diet--except the foods causing an allergic reaction--did not take anything and the problem went away by itself after a year and half or so.