I would consider pdoc to review your meds and a pharmacist as well. Lithium therapeutic range-high end is close to your blood work. Some people do suffer a side effect of concentration problem if blood work indicates consistently higher levels than necessary.
This is why regular blood work is done. But it is best if the doc who prescribed the medications reviews your meds and you discuss the changes in your concentration. And if the program you are attending has a pharmacy service to assist in this, that would helpful as well.

Take care.