Do realxers Thin your hair????????

What i mean by this is do they make the actual hair follicle thinner than it naturally is not if they knock out your hair I have had 2 relaxer treatments 7 months apart and hair did fall off during the procedure but not handful the only reason it fell out is cause the lady was tugging and tugging at my hair a lot of my hair did fall out but it was because of garnier and pantene brand shampoos not he relaxer treatment. I have a ton of hair but a lot of it is really short ( the growths are about 2-3 inches long while the rest are around 6-7 inches long). Also what can i do to keep my scalp healthy??