Think about whether there has been anything you have been doing recently that might have made the eczema come on, e.g. new skin products or washing powders or eating new foods. Some people find that their eczema gets better if they stop eating dairy.
You just got to think about times when it has been especially bad and what you did before, times when it has been good and what you didn't do, then trial stuff. For example a common one to try first is to change laundry detergent, or cut out dairy as mentioned.
Definitely speak to your GP. You can try to identify other triggers too - allergens have already been mentioned, mine flares up with stress. My skin is also sensitive to SPF-containing moisturiser randomly, there might be products that irritate your skin too that you haven't realised.