Second pregnancy 🤰 worried to death!!!

I found out I was 4 weeks pregnant last week. I wasn’t trying so I had been heavily drinking and I know that’s not healthy. I had my rainbow baby on January 15,2017 I had suffered a miscarriage the year before so now I am currently nervous I am 5 weeks and 2 days but I have been having a lot of soreness in my stomach even though we weren’t planning this baby we want this baby and I’m just worried I’ll miscarry again because of these cramps and backaches 😩😩😩 is there anything I can do to prevent this ?