It sounds like he has got some sort of infection , the swellings you mention are probabaly
His cervical lymph nods,
Lymph nods are filters (for want of better word )
If they are swolen then it is probabaly because they are buzzy filtering toxins (in an ideal world the lymph node's throughout the body will filter and eat any think that shouldn't be there , but when thay are swolen , then the toxins in his body are to much for his system to deal with , and need help !!
I would strongly surjest you get you pig to the vets A S A P, as it sounds as his lymphatic
System is under a lot of strain and anti biotics may me needed to help with the fight
The only other thing l can think of is that he has got an absess, but one one each side of the neck is not lightly,
I would strongly suspect the swelling are as l said cervical lymph nods .
I would get him to the vet tonight ,!!! .