This is largely a question of narrative style. You can treat it as a hypothetical situation (the verb imagine allows you to do this without an if), in which case you should use the subjunctive (if available) or the past
Alternatively, you can ask the reader to imagine that, right now, these things are happening, and describe in the present tense. This style is often used when telling jokes, for example:
A guy walks into a bar and asks for ten shots of the establishment's finest single malt scotch. The bartender sets him up, and the guy takes the first shot in the row and pours it on the floor. He then takes the last one in the and does the same. The bartender asks him, "Why did you do that?" And the guy replies, " Well the first shot always tastes like crap, and the last one always makes me sick!"
Whatever you do, you have to be consistent throughout the narrative.
"Now, ladies, imagine that you were seen by a 60 year-old male doctor, and he asked you many strange and uncomfortable questions. How would you feel? "
"Now, ladies, imagine that you are seen by a 60 year-old male doctor. He asks you many strange and uncomfortable questions. How would you feel? "
Like if, the hypothetical effects of imagine only last for the current sentence: that's why I have joined the two sentences together in the first example. An alternative would be to maintain the hypothetical mood by repeating "Imagine that.." at the start of each sentence. The hypothetical construction would therefore be difficult for a long scenario, unless you particularly want to keep repeating the "Imagine" for dramatic effect, as in the John Lennon song (which incidentally uses present tense). Otherwise, present tense would be preferable.
Note that "How would you feel?" must always be hypothetical, even in a present-tense narrative, because the listener's emotions are not part of the narrative.