Muscle weakness. Gets worse by evening.

Hello Doctor, I am a 29-year-old female experiencing persistent muscle weakness and fatigue. My main concerns are jaw fatigue while chewing, neck and hand weakness (difficulty holding head/hands up), breathlessness on exertion, and occasional cold sensations with paresthesia in hands/feet. Sometimes I feel like I'm experiencing difficulty in swallowing. Blood tests including thyroid, electrolytes, vitamin D, and magnesium are mostly normal. I'm taking medicines for anxiety (Sertraline 25). All of these symptoms make me very anxious. I initially thought it's anxiety related but my symptoms consistently begin physically. These symptoms come and go, which makes me feel more confused. These symptoms got worse in the last few days. It gets worse by evening.