WILL MY DOG EVER ACT NORMAL AGAIN AFTER HEART WORM TREATMENT!??!?

I adopted my dog 2 months ago and She was the most loving and obedient dog ever! When I adopted her they told me she was Heart worm positive so of course I made sure she was treated. Now she is not even close to the same dog. She doesn't listen or when she does it's out of fear I'm gonna hurt her. I try to do everything to keep her happy and calm as the Vet recommended but "Delta" acts as if she is completely scared of me. Is this do to the treatment? Will she ever be Normal? What can I do? Has anyone had these same issues and if so what did you do to resolve this?