I have a problem of eczema on my knees. Due to this, during the Sujood in Salah, a few drops ( lesser than a dirham) come out of my knees onto a bandaid that I tie on my knees before every salah. However, along with the blood, i have seen that small amount of water also comes out from my knees. I am not sure how this happens but I presume that it is because of taking a bath before prayers. However I do dry my knees properly before salah. Does the water coming out with the blood from my knees cause a problem and would I have to wash my knees before every prayer ? The water and blood come out on the bandaid tied around my knees

You do not need to do so.