High risk

I have had one miscarriage and one still birth. The doctors told me last time that all my pregnancies will be high risk and I will have to be in the hospital from week 23 until birth. They won't do much until the baby is viable. I am 6 weeks and 3 days. When I was pregnant with my daughter I bled heavily for 3 months and was on bed rest the whole time. I had my baby at almost 22 weeks. I am trying not to worry. Mainly because stress will hurt the baby.. They could not tell me what was wrong last time because they didnt know. I am feeling wierd cramps and pains I havent before and my stomach feels hard to me. I have a bad back and it feels horrible. Anyone else have problems like this? Worried but keeping positive and hopeful.