If you want to try a tricyclic antidepressant (TCA), you may want to consider imipramine rather than amitriptyline. Both are TCAs, but imipramine is better tolerated and has a lower incidence of side effects.
I used to take imipramine on days or weeks when I had depression. However, now I use the drug amisulpride off label as an antidepressant, and I find it is excellent. Amisulpride gives me a more natural feeling mood boost (I find the TCA antidepressant effects a bit of an artificial feeling). I take just 12.5 mg of amisulpride daily. Amisulpride also noticeably improves the sound sensitivity symptoms of ME/CFS, which is a great boon.