HELP !did i overdose on benadryl???!!!?

im 14, and i dont remember if i took 2 sud a fed cold and coughs at 8:30 pm, which wud have been my next dose since i took the other dose at 4 pm, so i took 1 dye free benadryl at abut 10 pm. am i gunna be okay? im jsut freaking myself out over this, im pretty sure. but i NEED reurance. i weigh about 140 pounds, and im 5'2 if that helps . i really need an answer before i go to bed. and i have diarrhea and my mouth is kinda dry, but i think i only belive that cus i looked up the over dosing reactions.