spider mites. the yellowish spots on the leaves is the signs of spider mites feeding. Good solution is flora mite, a bit expensive but good to have around, just mix with warm water and dish soap and apply with spray bottle with lights off. Apply up to 4-5 days to kill all adults and any eggs that might have already been laid and are about to hatch, these little bastards are tough to get rid of and you need to keep an eye out for them returning. I have sprayed plants that were in there 4th and 5th week without experiencing any problems any later then that you might want to avoid. Good luck and post any other questions you might have.