Re: Still having cramps?
It's a myth that you can't have your period while breastfeeding. Menstruation can return at any time when you're nursing. Some nursing moms will get their fertility back within a few weeks or months of birth, most will go many months without a period, and a few will not get their periods back until their babies/toddlers are completely weaned.
If you're on the combination estrogen-progestin pill, then the "period" you're getting isn't a real period. Technically speaking, it's withdrawal bleeding caused by that week of placebo pills that are included in every pack. I am not sure if the same applies if you are on the progestin-only mini-pill- but I think it does.
How has your milk supply been? Any issues? Some moms find that hormonal contraception has a negative impact on supply. This is particularly true of the combination pills. The mini-pill is much less likely to cause issues.
Regarding the cramping... Well, when you nurse you release oxytocin which causes the uterus to contract. That's typically painless, except for the relatively brief period during which the uterus is shrinking back to its antepartum size. So painful cramping at 3.5 months postpartum doesn't sound entirely normal to me. I'd contact your doc or midwife and get an expert opinion!
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"