Thank you for your question. Yes, it's very possible that what you are describing was due to side effects of the lithium. The fact that you feel much better after getting it out of your system would indicate that this was the cause of your negative symptoms.
It really sounds like lithium is not a good medication for you. There are other mood stabilizers of course on the market that may work better for you, though it sounds like you are feeling okay now, without the medication altogether.
If you have more questions let me know. Otherwise best wishes to you! Kristin