constipated 16 month old

what can help my baby go? shes been constipated bad. she had 1 "soft" poop this past week, or a poop she passed with no help. then she goes back to being constipated to where its hurting her and shes crying. we hold her legs back and sometimes have to get it out ourselves (sorry my husband does this, I can't do it myself..). Ive given her prune juice, apple juice, pears every day this week. the dr gave me some little packets to add milk/sauces etc. i try rubbing her belly, warm baths, doing bicycles with her legs (if she let's me)..I don't want to do a suppository:( but I hate seeing her in pain. I don't understand what's causing it... she has the same foods she usually has and has never gotten this bad. it's been like this for a week n a half already. when she tries to go she squeezes her cheeks together. I feel like shes holding it in and that's what's making her get backed up all over again. could that be possible? please help what else can I do