My son 6 weeks too, has the same problem. Told his pediatrician during a month assessment, was informed it's phlegm. So pediatrician used a tiny tube and sucked it with a machine. The moment pediatrician started, I super regret to let my boy go through it. He screamed, cry till all tears flowing down and while sucking, me n my hubby saw stain of blood too.
After that night, he refuses to let anyone to put anything into his nose. Used to remove the big dirt and he quietly let me do so, now i can only see but cannot touch. *sigh*