Brief Answer:
Not related to what the doctor did.

Detailed Answer:
I read your question carefully and I understand your concern since the limb symptoms happened the morning after the shot.

You don't mention the content of the shot but judging from your description of its effect and use it must have been Alprostadil. It is a medication which simply dilates blood vessels in the penis leading to erection, with an effect which lasts about 30-60 minutes.

As such its effect is local and its (rare) side effects are local ones. They do not affect the limbs and its effect on the morning after was over anyway. The blood flow reversal which your doctor did doesn't have any effect on other organs either. The massage simply compressed those dilated vessels to empty them of the extra blood causing erection, it does not have any effect on circulation in other areas, be it in the limbs or other organs.

So to answer your question, no, the pain is not related to the procedure. If persistent the cause should be searched elsewhere such as a nerve damage, vascular issues such as varicose veins, phlebitis, narrowing of the arteries etc, trauma or rheumatological issues. To distinguish between them more info is needed on the characteristics of the pain and a physical exam as well.

I remain at your disposal for other questions.

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Brief Answer:
That could well be the cause

Detailed Answer:
Thank you for that additional information.

In that case the situation changes, that injection could potentially be the cause for the symptoms as intramuscular injections in the buttocks could cause nerve damage (usually gluteal nerve) due either to directly hitting the nerve or through the inflammatory reaction nearby.

Now regarding how long will it last, that depends on the extent of the damage, may be transitory and completely recover gradually in less than a month or leave some degree of damage. To get an estimate for that, a neurological physical exam to check for other symptoms such as muscle weakness, as well as a test called nerve conduction studies and electromyography (EMG) is recommended. Corticosteroid treatment for a couple of weeks are often used to counter inflammation and reduce damage.

I hope to have been of help.

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Brief Answer:
Read below

Detailed Answer:
Yes, if needed you can take over the counter painkillers for the pain like Ibuprofen for example.

As for the corticosteroids, since it is a medication which is not taken that lightly due to the potential for side effects (and needs a prescription as well) you should see a physician first. That is to confirm the diagnosis by looking for other signs of sciatic nerve damage (like lack of reflexes, muscular weakness) and lack of other manifestations which might suggest some other cause.
If diagnosis is confirmed it is started initially at a high dose for the first week (dose depends on your weight), to be gradually lowered and interrupted in the subsequent couple of weeks. Long term use has side effects but in your case it would be for a short time so the risk is low.

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