Air Carrier Captain reported a fume event during descent until gate arrival. The fumes were reported by the aft flight attendants who experienced physiological symptoms.

Narrative

Upon arrival at the gate in ZZZ I received a call from one of our aft flight attendants during deplaning. The FA's (Flight Attendants) in the rear of the aircraft reported feeling ill due to a strong chemical odor which commenced shortly after the top of descent and gradually grew stronger until touchdown. They reported that the smell was sweet; very; acute; abrasive to the throat and nauseating. They believed that the smell was nearly strong enough to justify utilizing O2 bottles but decided not to.As soon as I was made aware of the problem the aircraft was written up and per the request of both affected FA's. Paramedics were called. Multiple attempts by multiple crew members to medical assist company yielded very unsatisfactory results. Long hold times were followed by little if any helpful advice that I have been made aware of.Get rid of medical assist company. From what I have gathered from the affected flight attendants medical assist company services added more stress and anxiety to an already stressful situation.