chances are it is dead yeast cells falling out . I would return it to the carboy and add a fining agent to insure everything fall out. as for the high acid I would make a sugar syrup using two cups sugar to one of hot water. mix in a blender when cool do bench trials, take a few samples of wine about a 1/4 cup each. add a 1/4 tsp to first, 2 time that for second, three time that for third do taste test. do more if necessary increasing sugar syrup by 1/4 tsp, syrup will not sweeten wine but correct the imbalance with the acid. find the right one calculate addition for main batch add sorbate and K-meta and bottle.