Hi I'm a 23 year old girl, I've been having muscle twitches in my right thigh and knee for about a week now only when relaxing could it be als?

NOT ALS. Might wonder about meralgia paresthetica, nerve issue at hip, or even benign fasciculations. However, you do NOT have ALS, so relax.
Anything. this is either a muscle fatigue or a dehydration and lack of magnesuin or potasuim, drink a plenty of water eat or drink food or drink that are rich in MG and K like orange juice or banana take NSAIDS like aleve (naproxen) use a heat pad and rest not better see your doctor.
Twitching. ALS unlikely check electrolytes,sodium potassium, calcium. Check Vit D and magnesium, iron. Decrease caffeine or energy drink intake get enough sleep follow up with doctor/urgent care.