Hello,
Thanks for joining me on e-healthforum.
A few more details about you might help:
1) Are you on any birth control measures?
2) Are you having any medications for eczema control?
Given the symptoms that you have (daily itchiness around my vulva, redness and hotness in skin, and no discharge) and the details that you have provided you (been tested, clean, no tight clothing, sexually active, and eczema history) the possibilities are:
1) That the eczema could have spread to your vulval region, which should be treated.
2) This is the possible side effects of birth control pills (if you are taking any).
For the temporary relief of symptoms, you can try applying Caladryl lotion (on cleaned and dried affected areas) 2-3 times a day, it will soothe the redness and itching.
For the cure of your symptoms, you should get yourself evaluated by your healthcare provider to find the exact cause behind it, and decide on the further line of management.
The investigations might include doing a vaginal smear to see if there is any infection present.
Wish you speedy recovery.