Though it is counter-intuitive, many of the shops in old-town Pamplona are closed during San Fermin when the town gets their tourists. The photo you see taken above was taken only around 2pm about 3 blocks away from Estafeta.
I have been told that many shops are open from 10am until about 2pm, but as I'm never up during this time, I never get to see those shops. (I wake up at 6am to watch the Bull Run and then go to sleep around 9am for a few hours)
The only shops that remain open are souvenier shops, which are filled with tshirts and other tacky souveniers; and even those shops don't remain open the whole day. You will be surprised to find that even ice cream shops and pastry shops are closed. Walking through the streets, it would seem as if the shops are out of business.
If you want to save on souveniers, plan to buy them in the last day or two or even after the festival when the price drops a few euros, but surprisingly, it won't drop by too much. The Kukuxumusu (popular brand with funny characters on the t-shirts) apparel all remains the same price.
Stores you can depend on being open in Old Town Pamplona are: restaurants, convenience stores and coffee shops.
Any questions? Please post your questions in the comments area, and I will be happy to answer you.