Reinstating Mirtazepine and not feeling good

hi all, so a week ago i was stupid cause i switch from mirt to trazodone cause of the weight, and crashed, i think it was like 1 or 2 weeks dropping and the switching, bad idea i woke up with my heart beet so fast and with a tight chest all day very dificult to breath. since then i reinstated mirt like a week ago and the heart racing is lessening but i feel soooo weak with my body, weak legs weak everyting and anxiety returned, i had no side effects when i began mirt besides the weight and vivid dreams so i dont know whats going on!

is it normal? is it adjusting again to my body? need to wait and continue taking to stabilize? i tough i stabilize quiker cause it was so fast...

anyone?