I am trying to fix a mates website, look at this page
http://bangkoktailorstore.com/index.php/prices-men
it has like 100 <br> tags under "Prices for men" in the inspect element, bu not in view source.
What could be causing this? It has a custom built CMS and I would think either some js or php would be having a conflict somewhere as it did not have the huge gap before.

Try to change your themes.

I tried for a few minutes to discern your problem, but that theme has so many errors within it, I'd really recommend trying something else.

I believe the CMS was uilt from scratch and has no themes.

If it's a custom CMS have whoever built it take a look. I'm sure they just made a mistake somewhere along the creation of it and may already know what has gone awry.