swollen and hard under belly

I recently got my two babies fixed, both female, about a week-two weeks ago. This is my first time taking animals to the vet for spaying, i felt so bad that I couldn't let them outside so i saved up and got them fixed. They told me that they could return to normal activity and everything would be fine. well one of them loves being pet on the belly and i was petting her when i noticed the area right below the half inch insition was swollen and hard when i touched it. The other hates being picked up, so i had to hold her at an angle, her's looked much worse and was really hard. Not sure if the way i held her effected that. What should I do? is it normal or should i call asap and get a checkup?

This is definitely an issue that you want to address with your vet ASAP. It's entirely possible that the swelling and firmness is just part of the body healing. However, it could also be a sign that something is seriously wrong, such as a possible infection. Given that it could be very serious it's best to just err on the side of caution. I would give them a call as soon as they open tomorrow and hopefully they will be able to get them in by the end of the day. In the meantime, keep a close eye on them both and their behavior. If either stops eating/drinking, begins vomiting, or becomes lethargic call the closest ER vet and seek immediate advice!  

Even though it's a little off topic, it sounds like you had the girls altered so that you could let them outdoors. While I give you tremendous credit for thinking ahead and not allowing them to get pregnant, make sure you take other precautionary measures to help keep them safe too. Meaning, make sure they are both fully vaccinated (and keep the vaccines up to date), have them microchipped, and get them collars and tags so that others will know that they have a home and are not strays/feral. While I think that it's great for cats to have access to the outdoors be cognizant of the area that you live in and the hazards that are there. In some situations (such as those that live in big cities or by busy roads) the risks just don't outweigh the benefits. If that's the case there are also alternatives ways to allow them time outdoors while maintaining there safety, such as by building a cat enclosure or using a harness and a leash. In the end you know if the benefits outweigh the risks, just be sure you take all the precautions that you can to make their time outside fun and exciting while still being safe! 

Vibes that these symptoms are just part of the healing process. Please, do let us know what the vet says or if you have any other questions. Welcome to TCS! 

Wondering if you managed to make contact with your vet, and how things are?