Sore breasts at five months

[cloutiedumpling]

DD is EBF and I'm finding that one breast in particular is quite tender. It is not the nipple but feels sore deeper into the breast and behind the nipple, if that makes sense. Any idea what could be causing it and how I can prevent it? Everything felt fine when she was tiny so I think that the latch is probably OK. TIA

I had a sore boob recently after months of no problems I've had mastitis & thrush so knew it wasn't those. I eventually realised it was due to DS constantly leaning on it. Once I stopped squashing it so much it disappeared...

Many thanks. Now you mention, it I haven't used a cushion for support for a while and maybe she is squashing me.