Nursing troubles

So I've been exclusively breastfeeding my son since birth. I have frozen milk as well that he will drink from a bottle if I'm not home (I'm a stay at home mom so I'm almost always able to feed him). For about a month now my son has started nursing differently. He always has a death grip on my breast that he nurses from and seems to be fighting between his hand and my nipple as to which he wants in his mouth. I want to nurse until hes a year old but its becoming painful. Any mommas have any tips on how to keep his hand busy instead of squeezing my breast? I nursed my daughter until she was a year old but never had any issues like this :(