Everytime I play barre chords I get cramps and I'm not pressing down hard at all as there 4th fret or higher. Is there anything that could be causing this as it's stopping me learning songs.

I have my thumb behind where my index would be to help hold barre but it's not pressing hard.
If you have just started using barre chords, just give it time and the muscles in your hand should adjust. You could also try stretching your hand and fingers before playing, or change your playing position. I used to get them too when I started using barre chords, its very uncomfortable.

If you have been playing barre chords for awhile and this is new, maybe the action on your guitar has changed or you have slightly changed the way you hold the chords.

Hope this helps.
While I cannot see your hand positioning or for how long you have had these problems, or even where specifically you are having these cramps. Is it the finger or the hand? The muscles that clench, or the muscles that stretch?

One problem I often encounter is that students tend to use the muscles behind every joint of their 'barring' finger. This results in having a curved finger, instead of a near perfectly straight one. As you would see if you'd do just that, is that the larger (and middle) part of your finger would not connect with the strings or even the neck.

What is ironic with barred chords is that at first many people feel they need a lot of strength, which results in above-mentioned curved finger, from a player using all their strength in every part of their finger and joints. While in fact the barre doesn't require so much 'clenching' muscles, as it requires the 'stretching' muscles.

Both the placing of the joints, where it is harder to push down the strings properly, as well as the proper use of muscles to 'stiffen' the barre instead of making it a curved and tensed finger.

To be specific, I found it working best to stretch the finger itself, thus using the outside muscles, and press it using the muscles from the palm-side of the hand, instead of the finger itself. Mind you this is dependent on what shape your guitar's neck has, as well as its width.
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i got hand cramps barring for decades. then i discovered that you can get a set-up with lower action, which really helped a lot (no one including 2 teachers ever told me about set-ups). i also discovered a few other things - i am more likely to have pain or cramps playing a guitar with a narrower nut or a D or U shaped neck. and when all else fails, extra light strings help a lot.
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