I feel like i have a lump or something in my throat, what is it?

hi all ever since my mom died from colon cancer i haven't been feeling good lately but she died about 8 months ago near my birthday, and iv been felling like a lump in the back of my throat, i know im not sick because i got sick about 3 weeks ago but my stomach ached but it dont do nothin here and i dont know what to do it's happened before, its not painfull or nothing, also after she died i started getting nervous alot for example if i was drilling a hole in the deck helping my dad i would consistently shake and now idk what to do because im even nevous when im with my girlfriend... iv asked the doctor but he said it will go away and that i needed to give it time. im even nervous when my cage fights start because i train for mma and idk what to do any tips?