I started meditation with earplugs 4 months back 15 -20 mins daily. It's said to improve concentration but 1.5 months I felt strange changes in myself which i never faced.I replaced words which were written. for ex. the first day I read as last day. I started stuttering, some words felt difficult to pronounce. Difficulty in comprehension. I am not able to think in advance like this action is going to be following that.. Which I could before . left meditation but these things haven't gone. Help