yes, i'm panicking, thank you for asking :-)

the other day, all my taties looked excellent.

as of just now(?!), there's two problems that have appeared all of a sudden:

small desiree patch:
a number of the plants are turning yellow all over, with the leaves curling
inwards & drying out. i carefully dug around to look at the baby taties of
the diseased(?) plants & the bigger ones seem to have slightly more textured
(wrinkled? what would be the word?) skin than one would expect, not smooth
like a baby spud still in the ground. others, otoh, looked quite normal to
me. i didn't dig around very much though, of course. (was that a bad thing
to do?)

big pontiac patch:
some of the plants have slight reddish-brownish areas on them, like a
sunburn or something (no defined edge to the marks - more of a shading).
these plants just look generally less well than the others, which look
perfectly normal. some of the leaves are yellowing & drying out a bit. again
i had a little dig, but couldn't see anything odd about the baby taties
underneath at all.

i've never grown potatoes before & i've looked in all my books for what it
might be, and online, and i just don't know. they've not flowered yet. one
plant has some buds. the desirees have been in for probably 3 months or
so(?) & the pontiacs perhaps two months, or 2 & a bit.