Rogaine does not seem to work anymore, should i stop using it?

Rogaine does NOT stop working. If you discontinue the treatment, you will lose all the benefits obtained. If your hair loss is active while on Rogaine, it may be  your androgenic alopecia. You may want to add finasteride, low level laser or PRP treatments to your regimen. Find a hair loss expert. They will confirm the diagnosis and work on a treatment plan. Ask to see photos.
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You absolutely should NOT stop using Rogaine. Although it doesn't stop all hair loss or progression over the years, it is very useful in minimizing hair loss and does not stop working. If you stop using it, all of the hair follicles that are dependent on it for growth and survival will fall out and you'll have a large shedding over a short period of time. Not sure if you're using it along with romaine, but propecia (finasteride) is a very effective oral pill and adjunct to Rogaine for prevention of hair loss progression.

You can use Finasteride instead of rogaine. 3.5 years is a long time period.  I will suggest you to get a concultation with your doctor.

In situations like this, nothing beats speaking to a physician about these issues. It could be that Rogaine stopped working but it could also be that your genetic hair loss has simply started moving along faster. There is one way to know for sure if Rogaine is working or not - and that’s to stop using it. If Rogaine truly was working you’ll lose hair at an accelerated rate. If Rogaine was not working, the simple act of stopping it should have little effect. Be sure to speak to your doctor before doing this. Starting and stopping Rogaine is tricky. Your physician may have advice about adding a second treatment. 

If the minoxidil has stopped working but you still have hairs from the minoxidil present, then if you stop it you will lose those hairs that are dependent upon the drug.  See your doctor and discuss