My 16 month old son met all his developmental milestones (gross and social) till 7.5 months. But he was not pulling up or sitting up on his own. He was trying to sit up on his own but could not and one fine day he stopped the trying. we always wondered why he cannot do it. then at around 10-11 months, we noticed swelling on his left thigh which was detected as "Muscular TB" and he is on AKT medication. After surgery and recovery we, started him on PT due to which eventually he did started walking but still cannot pull up nor sit up on his own. When I spoke to his pediatrician, she says that he would eventually do it but may be the muscles are weak and hence would take time. But my physiotherapist says that hes developmentally delayed in cognition and other social skills like pointing and waving bye bye. He has an excellent eye contact, loves to play with us, plays peek a boo and hide and seek., imitates hands clapping and stomp feet (not regularly but most of time), gives his hands to be picked up and babbles alot but no meaningful words. Till now I thought that hes behind since from 10-13 months he was in pain frustration due to his leg problem. He does not play meaningfully with his toys (may be one or two) but throws them around.recently with lot of pushing, he has started giving "high fives", "high tens" ... He tries to hit a communication with us in his own sweet language. and uses some gestures like clapping if happy etc. He does not like anyone touching him except me and his dad.I am suspecting him to have some developmental disorder hopefully not autism.