I had soem complications thru out my entire pregnancy...mostly just very sever hypermesis...but I did have cramping and bleedign in the first weeks also...I was strongly encouraged to wean...which wasn't anoption for me...we are still enjoyign a wonderful nursing relationship and my youngest is 21 mtsh.
however I really beleive you need to look to yoru self for the answer...you know your body, your child and your new baby better than anyone eles.
what does your heart tell you?
for us I knew that my complications had nothing to do with nursing and I trusted my body would tell me when I needed to stop....does that make sense?
I know it wasn't easy, but I had simialr issues with my first and ofcourse I wans't nursing thru that pregnancy
I was also very lucky to have a very supportive Ped, so that helped too.
But as a PP said, it sounds liek yoru body is healing, and you ahev continued to nurse.
I went on to have a very healthy 8lb 11 oz son who finally made his appeareance 12 days late:LOL after gettign to know who is is a bit better i now he isn't really worried about deadlines and tends to do everythign at his own pace, oh and he loves a nice warm cuddle place to snuggle best of all:LOL
good luck mama! I wish you to most wondeful pregnancy and if you do decide to continue to nurse, I promise ti will eb all worth it, wheather you tandem nurse or not, I think it helps to build a very strong bond between siblings