Hope you get better soon Nish. You forgot to eliminate the 8 out SDs tho.

Cards to flop a gutshot:

a) JTx
b) J9x
c) T6x
d) 95x
e) 64x
f) 54x

In each case, 1 value of x will make a straight. ie 9 with JT makes JT987.
In cases b) to e), 1 value of x will make a double gutshot. ie 5 with J9 makes J 987 5, so we have an 8 out SD
In cases b) to e), 1 value of x will make an OESD. ie 6 with J9 makes J 9876.

Flops containing JTx, where x does not make a straight (ie the flop is not a combination of JT9):

(4*4*44)*(6) = 4224

(44 because the four nines are excluded).

Times six because there's six combinations to get a gutshot:

4224*6 = 25344

But there are 2 additional cards in cases b to e that make an 8 out SD. Number of J96 or J95 flops is

4 * 4 *8 *6 = 768

So 768 *4 = 3072 flops contain an OESD, so the number of flops that only contain a 4 out SD are:

25344 - 3072 = 22272

The chance of making a 4 out gutshot is

22272/117 600 = 18.9%