yes it's common after delivery.. am also facing the same.. it was worst in 4th and 5th month after delivery... but it gradually get controlled by its own... whenever possible apply warm coconut oil and use mild shampoo.

Also drink lots of water, start mild workout and dont use heating products or voluminizing shampoos

have u tried this castor oil and coconut oil mix n apply, can use mamearth hair mask also it's good