You can get eczema at any age and for a multitude of reasons. I am not a medical professional but have first hand experience after developing my first form of eczema, ACD, at age 51. I also learned I had Adult Leukemia that year. Leukemia is an auto-immune disease. Before age 51 I had hay-fever, an environmental allergy, but my skin was good and never had rashes or even acne. No known contact allergies previously. I don't know your age but eczema can strike at any age, even babies often have a common form called Atopic, but adults can also develop Atopic. Atopic is a challenge, as it often starts at a young age and the standard steroid treatments end up causing major side affects or stop working. Yet the good news for the Atopic is a new, expensive, but miraculous treatment called Dupixent which works for many.

A very rare thing happened to me, my Adult Leukemia, an incurable or chronic form started improving without any treatment 7 years ago and disappeared 4 years ago at age 66, about the same time my ACD went wild, believe me life was not worth living and I also developed 2 additional forms of eczema
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Eczema is an autoimmune disease so if you have have it you do have a compromised immune system. Surprisingly I haven't had a cold in 20 years and when my entire family (even with flu shots) was bedridden with the flu I might have had it but my symptoms were so mild, just feeling tired and lacking an appetite may have been based on sympathy and the effort required keeping others clean and cared for.

As mentioned, keep searching and learning and to give you hope realize all 3 forms of my eczema are under control now, but seems there is no universal treatment, yes some more effective than others and all of us need our own treatment plan. Trial and error.