missed period/not pregnant, some weight gain, bloating/gas, recent mono, whats wrong?!

i'm 19 years old and in march i missed my period, took a pregnancy test that came back negative. since, i have been to a doctor because i had strep throat, was always feeling tired, my bowel movements slowed down and i am always bloated, and i am gaining some weight. the doctor made me get a blood test and told me i had mono but they also checked my thyroid levels and those came back higher then normal but i was told the mono would cause that.i have been recovering from it and feel alot better now and im not always AS tired and i have somewhat more energy then i did but all my other symptoms(weight gain,bloating/gas,slowed bowel movements) still persist. i dont think im pregnant because i believe i would definitly know by now if i was plus my test was negative. also, thyroid problems have been present in my family before and i was retested to see if my levels were still high after the mono had run its course but still nothing. could mono or a thyroid problem cause me to miss my period and experience these types of stymptoms? if not what could?

I have no idea if you will ever see this or if you are still having problems, but if you are still having problems and do see this, PLEASE check out Celiac Disease on the internet. I battled for years before I accidentally stumbled upon it on the internet just to find out I would have died if I didn't catch it myself. Good Luck!!