Strong blood flow when meditating I am currently following a vipassana retreat at Panditarama Lumbini (where you are asked to notice the rise and fallings of the abdomen). The first 5 days were OK (even if I maybe was pushing too much with crossing the legs, hurting for one hour periods) but I have a problem since two days ago (even if I stooped pushing hard crossing my legs): When I sit down for meditation, my blood flow increases so that I can feel it everywhere on my body including head and abdomen, to the point that I feel both the breath and the blood flow when putting the hand over my abdomen. Also, I started salivating a lot (only when I sit down for meditation). Also after only one or two minutes of starting the meditation, my breathing speeds up (instead of speed down as usual).

I have had this problem already for two days now. What can be the real problem and how to solve it? 
Shall I stop the retreat? 
(I feel that stopping now the retreat without having experienced a nice insight would be a bad idea because I probably wouldn't retry the retreat never again)
According to my teacher, increased salivation is a good sign. This means your mindfulness of body and of feelings is recovering.

Increased sensation of blood flow is alright as long as it does not cause a headache. A headache would mean you are trying too hard and fighting with yourself. If that were the case then you would want to either chill down a little or take a break.

Breathing speed up soon after sitting means you're no longer blocking it. Allow yourself to make a lot of noise, don't try to be quiet or calm down too soon. Let your breathing by very noisy until it calms down by itself.

Overall it sounds like you are making good progress, just keep going, don't fight yourself and go with your intuition. If I were you I would not stop the retreat now. Just don't generate expectation to get some external insight. The insight is the elephant in the room you can access through being aware of all experiences, esp. ones that you habitually push outside your attention.

While abdomen is the anchor that keeps you from flying away, it does not mean you should block other inner experiences.