help needed 4th week flowering

Hi guys first time grower got 3 afgahns into the 4th week of flowering . They r about 3 foot tall . But in the last week I have noticed a lot of the leaves r dieing and falling off . Is this normal . Most of the other leaves look quite healthy.. but a few have got black spots and sum r yellow . And. One more thing the buds look quite far apart there is about 4 to 9 buds forming on each big branches . Don't no if I am just over worrying . Or if there is probs . Sorry no pics. I don't no how to upload them from my phone . And not got a computer the now . Any tips or help . Would b very much thanked . And any pics of what a 4 week flower on a afgan looks like thanks
 
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