So he's never had dental cleaning b4? He probably has a bad tooth or teeth, it probably hurts & he doesn't let you brush his teeth...Momo had to have 3 back molars pulled on his last dental cleaning & he lets me actually put the toothbrush in his mouth now. B4, he fought me til he was panting & I was sweating loll. I brush my guys teeth every night b4 bedtime.
You should really put aside some money for his dental cleaning when you can, it's very important. His gums bleeding is a sign of gingivitis & like Kat mentioned, periodontal disease can carry bad blood to their heart & other organs & cause major health problems.
Dog Gum Disease -- Gingivitis and Periodontitis ?Symptoms and Treatments
I wouldn't try to keep brushing his teeth if he's bleeding (bad blood)...besides, all that plaque will not come off w/a toothbrush, he needs antibiotics asap.