Because of Sebum, Get the oil and sebum under control. It can make large pores and ice picks appear larger. A Acid that unplugs the sebum can be helpful. Salicylic acid etc do this (washes and peels). Glycolic opens up the keratin plug. Ice picks happen by scarring on a hair follicle normally.

The only other thing I can think of is your inducing them to look larger and smaller by over treating, exfoliating so the epidermis is removed showing the scar. Some have a different condition where they have spontaneous scarring, blackheads, and pore issues.

It would be best to see a dermatologist to check out the issue. Hydro peels are also cheap and effective to clean things out.