Baby sucking finger

My Lo is 18 months old. She sucks her 2 fingers all the time. Because of that she is reluctant to walk or do any activity and even sometime if she stands with support, she uses only one hand as other hand is engaged in sucking the fingers. She is less active because of that. Is there any one who had same problem? How to stop this habit? #worriedmomhere #newmom #FTM #pacifierproblem