Ref. No. 1232/42-548
In the name of Allah the most Gracious the most Merrciful
The answer to your question is as follows:
Blood is interpreted as haram wealth. If you have haram or doubtful wealth, give it in charity. And if not, it's a satanic dream. So, before going to bed, recite Ayatul-Kursi and the four Quls, blow on your hands and spread them all over your body. Insha Allah, such dreams will not pester you. May Allah protect you from all evils!
And Allah knows best
Darul Uloom Waqf Deoband