Do NOT raise the temperature. Raising the temperature of your tank is fine if you're treating ich - fungus and bacterial infections, however, respond in the undesirable manner of actualy spreading faster. If anything (actualy, you should) lower the temperature to below 75 deg F (gradualy).
As fungus infections normaly only occur as secondary infections, it's almost deffinately a bacterial (columnaris - and aeromonas sometimes) infection. Medications used to treat 'fungus & finrot' are made to treat this but most antibiotics are equaly useful (if not better) as long as you are careful to monitor your water quality and eprform water changes as necessary as antibiotics can cause issues with biological filtration.