How come when i run. my gums feel itchy and when i rinse it with water. my saliva is really sticky almost like blood mix with it.

Running and saliva: This sounds like dehydration. Make sure you drink plenty of water throughout the day every day.

Dessication: Breathing through your mouth as is typical for a runner can dessicate the mucosal skin in your mouth producing variable symptoms. If you can slow down and breathe through your nose more, it may help.

Metabolism at work!: When you run or exert yourself, your bodies nervous system responds in kind. Usually, your blood is redirected from your stomach and other non essential organs to essential ones, your saliva becomes thick and your heartbeat increases. Once you settle down, and allow your heart rate to normalize, your body will respond as well.