Trichlor will work to raise CYA and chlorine. It will also lower pH.

Like PoolDoc said, do be careful buying dichlor at Lowes or Home Depot. Many(most) retailers are selling adulterated dichlor many formulations containing copper. Sam's Club Pool Brand dichlor is OK (last checked). PoolDoc's Amazon links are also the good stuff. For about twice the price per pound, the Leslie's near me sells 99% dichlor (good stuff). I can't say if it's the same near you. Many pool stores sell the diluted / corrupted material.

If you do venture into a pool store, do not let them sell you anything other than 99% dichlor (56% available chlorine or better). They will try.

How much trichlor do you have on hand? How much stabilizer?