Spider Alert!
What concerns me from the most recent episode is the poison which has no known cure, including somehow preventing the doctor from regenerating. Considering David Tennants doctor regenerated from radiation poisoning, not to mention he's been known to absorb radiation and get rid of it into his shoe . The only thing I can think of is the Doctor himself is actually running out of or had run out of regenerations. River however having used all of her regenerations to bring him back, might somehow have transferred some of those regenerations into the doctor.
What concerns me from the most recent episode is the poison which has no known cure, including somehow preventing the doctor from regenerating. Considering David Tennants doctor regenerated from radiation poisoning, not to mention he's been known to absorb radiation and get rid of it into his shoe . The only thing I can think of is the Doctor himself is actually running out of or had run out of regenerations. River however having used all of her regenerations to bring him back, might somehow have transferred some of those regenerations into the doctor.