Brief Answer:
probably not shingles...

Detailed Answer:
Hello,

let me start with this: the way the lesions look is not always diagnostic for dermatological disorders. The site of involvement and how the rash evolves may be very important.

The individual lesions look like herpes (although I'm not sure whether these are small papules or vesicles). Herpes usually causes symptoms including pain and a distorted sensation. The involved area may feel like sunburn skin and is usually painful even without touching it. In most cases the symptoms develop a few days before the rash.

If you've had shingles on the same part of your body then this is definitely something to consider because herpes usually develops on the same spot. Herpes is usually more widespread and I would expect it to appear on a larger part of your thigh.

On the other hand a local inflammatory disorder or an allergic reaction may cause itchiness without pain (or without significant pain).

So concluding my answer, I can't be sure. Arguments in favor of herpes include (1) the pattern (but not the extent) of the rash, (2) your history of shingles. Arguments against herpes include (1) the limited distribution of the rash, (2) the lack of pain, (3) the lack of symptoms before the rash (if I'm right to assume that).

Since there is itching trying local treatment with an antihistamine sounds like a good idea that wouldn't affect herpes.

I hope you find my comments helpful!
Kind Regards!

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Brief Answer:
it could be just local dermatitis

Detailed Answer:
So although such things are better diagnosed in person, it seems that this is more likely to be a local dermatitis (allergic?). Improvement with benadryl is a good sign. You should be vigilant for any changes (appearance of lesions, distribution, symptoms) that may occur over the next days and contact your doctor if necessary.

Best wishes for a fast recovery!

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