Hi Jan,

Yes, that's not only possible, but I would venture it's also likely. You're under extreme stress which can exacerbate some symptoms and cause others. I think the heart palpitations are worth at least a call to your doctor. FWIW, heart palpitations have also been reported as a side effect of Cymbalta.
Google: cymbalta side effects palpitations

Unfortunately, gabapentin does have that "foggy" effect on many people. It was so bad for me that I had to stop taking it, OTOH it doesn't seem to bother my wife at all. Gabapentin should not be discontinued abruptly.

What is the Cymbalta being prescribed for specifically? If sleeping is the problem, some folks are taking a low dose of amitriptyline. Taking both Cymbalta & amitriptyline may not be a good idea; there's a rare possibility of serotonin syndrome, but amitriptyline instead of Cymbalta might be something to ask/discuss with your doctor.

I think it's a good idea to read up on any/all prescription (and other) meds & supplements we're taking or are contemplating taking (recommended/prescribed by doctors) before starting them, so we know/understand what to expect and can ask questions ahead of time.

Due to the personal tragedies, it may be beneficial to review the stages of grief so that you're aware and understand when you feel some of those emotions/feelings/things happening.
Google: stages of grief

Condolences,

Doc