If they are smart enough to be tracking your social media apps they may well be wily enough to use a proxy or VPN to conceal their actual IP address (although most likely they just figured out a password, which is how most social media accounts are compromised). Still, you can just use a website to enter the IP address and get a general idea and see if anyone you know lives in the area. This one is more accurate than some others, but there are plenty of options: http://www.ipligence.com/geolocation
To find out someone's specific identity and location through an IP address is possible. As you probably know, an IP address is analogous to a telephone number. However, knowledge of the person's identity and specific location tied to an IP address is generally limited to their ISP. For most people, this means the only way to find out a physical address associated with an IP address is through a subpoenaing the information from the ISP. Obviously, this is pretty difficult since a court isn't going to issue subpoenas willy-nilly. If you are concerned that this is a legitimate case of stalking you might want to talk to the local police, although they are not likely to take it very seriously absent something more than just your suspicions.
I would change all of my passwords immediately if I were you...ALL of them....and make sure it isn't something that can be easily figured out by someone that knows you. Also, use 2-factor authentication on those accounts that support it to make it more difficult for anyone to gain unauthorized access.