I will not tell you what early symptoms are, because if you are like me you will immediately feel them.
She should know about them because not knowing makes anxiety worse.
Like Scooter said, cramping and fasciculations are not first symptoms. Not even close! First symptom is weakness in muscles. And not just any muscles, it's weakness in your lower legs or hands. Your anxiety will not make these syptoms occur. This is not the weakness you feel, this weakness manifests itself by you not being able to stand up or write your name or turn a doorknob or button up your shirt. Try standing on your toes and your heels. If you can do it, you're in the clear. You feel nothing because it's not your sensor neurons that don't work, it's the motor neurons. And this never happens over night, it progresses over the months and years. You might feel as if you can stand on your toes but then for a second your muscles stop working but you don't fall because this break is short. This feeling is anxiety and is nothing like ALS. Don't think about it, just do it. Lean on something because not many people have that balance (especially with flat feet). When you have ALS in your legs, you can't walk over a flat surface so you can forget about standing on your toes and heels. You just can't. It's not like it's hard for you, you simply cannot do it. Cramps and fasciculations come much later. I have read that the first symptom is "awkwardness while walking". This is bullsh**. I always feel awkward while walking because I have flat feet!
I have had similar symptoms on my calf once and also thought it was ALS (but I have a good reason, my dad died of it so it would make more sense). My calf would feel strained and cramped. Then it was tingling and the fasciculations came. It was horrible! But then I found out that it was a strained calf due to a flat foot. It can affect both sides of your calf. My outer part of the calf was strained because there is a tendon that goes by the inward part of your heel and then connects on your foot arch on the inside of your foot. Naturally, when the arch is down, it pulls the tendon down and stretches your calf. It's only logical!