I'd call the place I'm donating blood to and ask about the infection thing. But I don't think its a problem. As long as your aren't anemic or dehydrated. DON'T donate blood in a dehydrated state. You'll have a long recovery period! Make sure before you go in that you drink a lot of water.
I think its a good sign that the pressure is lessening - and the itches could be a sign of drainage and healing as well.
1. Love ME no matter what noises are screaming at me, or who is trying to tear me down.
2. Eat to heal
3. Move to live
4. Embrace today
5. Live with intention
6. Respect my body
7. Cultivate joy
8. Find my passion
9. Meditate on peace in my soul