Do i have mono? mononucleosis?

for the past week i have been kinda weak and today i was so weak and my legs and joints where really aching. not to mention i have had severe headaches and fatigue. although, i dont have a fever and i i dont have weird tonsils. also i havent lost my appetite but its been acting weird and unusual. but in total i just cant even walk to my backyard, well i can, but im extremely tired which is not normal knowing that im a very athletic 14 year old girl. p.s i went to the doctor and they thought it might be mono but not sure. so if you could tell me if its likely i do have it, that would be good.