Talk to Cardiologist on Weakness, Fatigue

I am diagnosed with atrial fibrillation 3 years back. Taking medicines (concor, lanoxin, xeralto) since 2.5 years now. I got stroke 3-4 times in the start. I used to get complaint of severe migraine before that which is perfectly fine Alhumdulillah with these medicines . But i was active, never had weakness issue. I used to go to gym on regular basis and my routine was tough enough for like 18 hrs and never got tired. And now,I can't even breath properly. My neck is getting in bent posture bcz i dont even have enough energy to support my body. If i write 3-4 words on page, my hands get hell pain.If i pick even 250gm of weight my shoulders feels like burning sensation. Crunches and yoga etc is so painful task for me now since last year. Even though I dont go to any work anymore. But i try exercising and treadmill on daily basis but muscle pains dont allow me to do so. If i do work i get severe breathing issue. Please tellme if something can be diagnosed with these symptoms and cure