My 18 Year Old Daughter Was Diagnosed With Lymes Disease

My 18 year old daughter was diagnosed with lymes disease and has been prescribed 100 mg of gabapentin 3x a day 2 weeks ago. She only has had to take 1 in the morning because it helps with her anxiety and aches but makes her very tired. She took her 100 mg dose 3 hours later than usual this morning and his depressed. Could it be due to the timing change or the med? She has tried ssri and quit due to very bad side effects