Concerned I might have ALS

Hello everyone,
I am a 20 year old female.

2 weeks ago I started having body-wide twitching, but then concentrated into my calves, keeping me up at night.
Tried working out 2 different times after twitching started leading to bad cramps in right thigh. Muscles also became extremely sore after workout.
Random cramps all over my body at rest and start of perceived weakness in right hand/arm and right leg.
Feels weird to walk and my right hand cramps up from typing and holding my cellphone. Things also feel heavier when I pick them up with my right hand than my left hand, which is bizarre because I am right handed.

I have been to my GP who chocked up my symptoms to anxiety and gave me a full exam and said everything felt normal strength. Is there a possibility that it hasn't progressed enough to feel the weakness that I have been feeling? I even tried to convince myself that it was anxiety so I went to a step aerobics class and my right foot felt like it didn't belong to me, I fatigued very quickly, and was very uncoordinated(which is out of characteristic for me).I even had to end the class early. I keep trying to do some basic exercises and my right side feels substantially weaker than my left, and I overall fatigued from walking for 5-10 minutes.

I am supposed to go back to the GP tomorrow. If he does another physical exam and says I'm okay should I still push for a referral to a neuro or more tests like an MRI? I know my age is on my side, but I keep seeing more and more people close to my age getting ALS, and I feel like I have the classic early symptoms. It has begun to make me depressed and extremely anxious and hard to function... so any advice would help!