can you call your dr about the lithium side effects? that's not good at all, and isn't something you should necessarily try to push through. I would suggest calling their emergency line and leaving a message. the lithium might well be just a horribly wrong drug for you. If it's all as dark as it sounds to me, I would suggest calling tonight if possible, even just to leave a message. ((hugs)) I had a few meds that made me way worse than better. It's really important to have an open dialogue with your doctor around stuff like that, especially when suicidal thinking is involved. I'm the last person on the planet to try to take that "choice" away from you, but if it's being brought on by something you can easily change, please look into doing that asap. There are plenty of other meds out there to try that may not have you feeling so awful. You deserve to fell better, not worse.
I'm sorry things are so rough with your granmda being sick, and missing your dad. Maybe your could reach out to him a bit more? He may welcome the distraction from having to care for your grandma. ((hugs)) you deserve to be happy(ier) hon.