Suggest Treatment For Tongue Tie

Hi, My daughter turned 5 mos. on Feb 5th, and she was just diagnosed w/ tongue tie yesterday. She may have been misdiagnosed w/ food allergy before b/c of weight problems. Do some infants not get diagnosed until this age? Our former Lactation consultant never saw it, and neither did the Ped .s. Her lowest weight after birth was 4 lbs, 11 oz., so she did have a small mouth.