Did you have these ants under the skin feeling on zoladex? or only since stopping?
I and others have expeienced the skin tingles like ants rushing all over you under the skin, but this is symptomatic of the GnRH drug which by now should be well out of your system.
One of the many functions of the Pituitary gland is the production of Adrenocorticotropic hormone (ACTH), which is needed for controlling your metabolism, blood sugar levels and blood pressure etc.
It is also called cortisone..and you need that to fend off urtcaria or hives as Valeriana suggested and is probably right - althought you don't necessarily have to get the stage of having a raised rash appearing all over your body which would be what we commonly call hives, for it to be an unpleasant sensation.
Shutting down the pituitary gland which is what Zoladex and the other GnRH drugs does do, is what causes the dramatic drop in ACTH/cortisone and the onset of hives (urticaria) and or the feeling of ants crawling all over you under the skin. Cortison is needed to control the teeny capilliaries in the skin. Without it - the under the skin weird sensations are highly likely to occur because your blood is needing many hormones produced by the pituitary to control its contents and its pressure and activity near the skin.
So I would recommend you visit your GP to have your blood tested for hormone levels especially ACTH levels. This would tell you if the pituitary gland is still waking up and has not yet pumped up your body with enough cortisone.
You can have cortisone injections to top you up, you may also find that simply taking an antihistmine tablet or two for a few days does the trick, but check if that's okay with your GP first as he/she may want a blood donation from you before that.
The cortisone (when there is enough of it) controls levels of histamine- without enough of it your histamine levels can soar, and taking anti-histamines can bring that level back down again. Well that's the thinking behind it at any rate, in laymans terms.
My ants crawling episodes were very frequent in the 4th months of zoldex but did ease off and disappear in the few weeks after stopping as it does for most of us, but the hormone production from the pituitary wakes up in stages, which is why it can take some ladies a long time for their periods to return - because the production of FSH nd LH from the pituitary are not high priority in the waking up and getting working again process of the pituitary gland.
I suspect that is what has happened to your ACTH levels. The ACTH factory in the pituitary has nodded off back to sleep a bit.