I have been using Qiskit over the last few weeks to run different programs. But right now, whenever I try to run any code, it gives me a 403 error stating that I am out of credits. I am creating a random walk simulation.
The 403 error is a http error - Forbidden. It's comming from the server that is giving you access to the quantum computer, not from the quantum computer its self.
If you are using IBM Q Experience you shuld check out the FAQ page. Regarding to credits it states:
A User has a maximum of 15 credits, and these credits are replenished upon the greater of 24 hours or when your execution has run off the queue.
So you have probably consumed your allocated credits and the http server is rejecting your requests.