Mazal tov on the recent birth of your baby!
It is common for postpartum bleeding to last 4-6 weeks, and it is normal for it to stop and start up again during that time period. While it is definitely possible that your bleeding is slowing down, it is still pretty early, so this may just be a temporary pause. We recommend giving yourself another week or so to see if the bleeding has actually stopped, and allow your stitches further time to heal, before trying to start the taharah process. In the meantime, try to eat a lot of fiber, fruits and vegetables, etc., and drink a lot of water to help minimize any hemorrhoidal bleeding.
Once you are ready to perform your hefsek and start counting the clean days, you can try to maneuver the bedikah cloth to avoid the area of your stitches in order to minimize the chances of finding blood on the cloth. If you do find blood on the bedikah cloth, and you suspect that it is due to the stitches, you have to confirm that your stitches are the only source of the bleeding in order to continue counting the clean days. There are two ways of confirming the source of bleeding. You can gently press a cloth to the stitches, and at the same time use a separate cloth to perform the bedikah. If there is blood on the cloth by the stitches, but no blood appears on the other cloth, you have confirmed that you are only bleeding from the stitches and not from the uterus. In this case your earlier stained bedikah has not invalidated the clean days. (If there is blood on both bedikah cloths, you have not ruled out the possibility that you are experiencing uterine bleeding as well.) The other way of confirming the source of the blood is to have your doctor or a bodeket taharah visually examine you to see if you are only bleeding from the stitches and not from the uterus.
If you are unable to confirm the source of the bleeding, you must assume the stained bedikah invalidated the clean days if the stain was clearly reddish or black. If the stain was a questionable shade, you can bring it to a halachic authority for evaluation.
If you are experiencing staining on your underwear as well, you can change your underwear more frequently to prevent any stains from accumulating to the size of a gris. This way stains smaller than a gris may be disregarded. Even if a stain is larger than a gris, if you have reason to believe it is due to hemorrhoids (e.g., due to the location of the stain, or finding blood when you wipe the anal area) or your stitches (e.g., if you press a tissue to the stitches you find a stain), you may attribute the stain to that source and it does not invalidate the clean days.
Please feel free to get back to us with any further questions.