22 weeks: Baby curled up in a ball

Noticed a hard bump on my tummy, it happens quite frequently like my baby curled up in a ball. It could be at anytime a day, either make a short appearance like 10-15 mins or longer. Usually disappears whenever i touched it (i thought my baby is playing with me) It gets pretty uncomfy too. It started since 15 weeks or so if i remember correctly. Not sure if this is completely normal?