Hi and welcome!
Please have your girl checked for ovarian cysts by a piggy savvy vet. They are not at all uncommon as sows are getting older. Symptoms can vary and many sows don't present with any but large cysts, but a seemingly perpetual strong season with all the chasing/mounting and assorted mating behaviours is one of them.
You can consider with your vet whether a full spaying operation or less invasive hormone injections/a hormone implant (chorulon/HGC) are preferable. In old and frail sows with large cysts for whom an operation is not an option an, draining of very large cysts under minimal anaestethics is a valid alternative. It is not a permanent solution, but each drain works for a number of months.
Guinea Lynx :: Ovarian Tumors
PS: the crying is either complaining or submission squeaking. Ovarian cyst behaviours can become very disruptive for a group and can cause huge stress or even lead to a break-up if the behaviour becomes aggressive.
