I have sinus infection. Blowing out a lot of blood and also nauseas. Should I be concerned? What should I do?

Sinusitis. See a doctor. Sinus infections require decongestants, analgesics, nasal irrigation, possibly nasal steroids and perhaps antibiotics. Go and get this taken care of before it really becomes severe.
SINUSITIS. Nose bleeding is perhaps due to excessive nose blowing. Mostly due to viral inf. Take over the counter antihistamines with decongestants. If you have fever, face pain, severe headaches, and thick yellow-green nose discharge or cold symptoms longer than 2 weeks consult your physician.