One of the conditions for Haydh is that there has to be continuity i.e blood has to be present in the inside such that one cannot say they have been clean for even 10 mins. Since your blood flow as you say is coming and going, it is not Haydh and hence is istihadha.
The type of istihadha depends on blood flow. If you are to put a piece of cotton to check, does the blood stay at the top of the cotton. If it does then it's istihadha qaleel and for this, whenever you are clean/pak, change your undergarments (if they have become najis), do wudhu and pray.