As above, try to eliminate the cause with different shorts to stop the material abrading with your skin, then try short-term barriers such as Vaseline or even cycling chamois cream.
Prantal powder is also good for chafing -- used to be sold to heal amputation stumps until marketing people got involved! About $15 a plastic squeeze bottle from the chemist, but I use it for chafing, sweat rash, waxing rash, almost anything when the skin is pissed off about something and everything has healed quickly.