Questions about going to urgent care?

i'm in a big city by myself for the first time this summer..i'm 20 years old. i'm still really afraid of going to the doctor though! for the past few days i've been having a rapid heartbeat. it's been about 115 bpm, and i cant feel it beating..it's driving me crazy and making me nervous. i've also been getting headaches and i just feel kind of weak..like gripping with my hands and stuff..my mom thinks i'm dehydrated because its so hot and i've been walking and sweating a lot but i tried drinking a lot today..i don't know. i don't know what id say at the dr because i get so nervous at the dr my heartrate is fast anyway. what do i do? i'm scared