Guinea pigs should not be kept on their own
Definitely do some research on that,it's extremely important to understand the care requirements for guinea pigs as they're definitely not an easy pet to keep and it is so easy to do it wrong!
As soon as you can introduce a second guinea pig that should be done,preferably using a C&C cage which are extremely cheap and offer much better space for piggies than any storebought cage
Make sure you're feeding a high quality pellet as a base for your guinea pig's diet,and giving unlimited age appropriate hay.A lot of pet stores sell really unhealthy mixed foods which contain things piggies can't digest such as seeds,so they absolutely must be avoided.
https://kmshayloft.com/ The best place to get pellets for guinea pigs.They're better than Oxbow,however they are only available online,but they're completely worth ordering.
If you haven't already,make sure to take time to check out some of the wonderful guinea pig youtubers as there is a load of useful information available!
https://www.youtube.com/user/skinnypigs1
https://www.youtube.com/channel/UCqy...yZIMOSdbBFxuzA
https://www.youtube.com/channel/UCp_...n2Ta8ZJWixiDnA
https://www.youtube.com/channel/UCPm...BUAo0pEWRxf3MQ
There's lots of information available on bonding guinea pigs and why it is absolutely important to have multiple piggies if not cruel to keep them separately almost all the time except for those extremely rare situations where it must be done.Your situation is not one of those though,and most people would never encounter such a situation.