My baby is tired all the time, should I take him to see the doctor?

Yes, see a doctor. No normal baby is "tired all the time". Baby humans, like baby animals, are active, happy, and excitable little guys. If a young baby seems always tired, have a doctor evaluate because there may be a problem with anemia, heart defects, chemical/salt imbalances, blood sugar, hormones, toxins/poisoning, a neurological problem, or even an infection.
Babies need sleep. It is normal for newborn babies to sleep 16 to 20 hours a day. When awake the baby should feed well and have active and playful periods. If this is not the case, further evaluation may be necessary.