Chances are that your old shower head might be the reason for the low water pressure. If that is the case, you will need to replace it as soon as possible.
The shower head replacement process should be undertaken with a lot of care. First, you need to find a reliable shower head.
Preferably, purchase a digital shower head. It is very efficient and effective.
This type of shower provides you with a chance of increasing your shower head water pressure anytime you want.
It is easy to use and has minimal complications. Definitely, the type of shower head you need.
[Side note: to know more about how often you should replace your shower head, click here.]
Recommended reading: Does Size of Shower Head Matter?