Muscle twitching in shoulder with arm weakness?

I am a 24 year old male and I've had twitching all over my body for about a year now.  It comes and goes in spurts and never had any problems until about a month ago.  I felt a twitch below my right shoulder blade that lasted for about 5 days.  It started off violently until it subsided to the point I had to use my hand to feel it.  Afterwards, my arm felt funny.  I thought it might be a bit tired from all the twitching.

Now, my arm feels weak in that I can still lift objects but they feel much heavier.  I don't know if this is perceived or true weakness.  My shoulder also droops significantly more than the other side now, and as a result causes some neck and mid back pain.  I am scared to death of ALS and have health anxiety, but I am just not sure what this could be indicative of.  I previously thought it was BFS, but what is this arm weakness and shoulder droop?  Is something actually wrong with my muscle such as atrophy?  I don't know.