Stem browning from bottom up

to start off ill take pics tommorrow. the plant is about 4-4.5ft tall and at the very bottom of the stem it is brown. i transplanted it awhile back maybe like a month ago in the ground into some clayish dirt but i used a tiller to break it up....ive been watering it with water from a nearby ditch and i kno the water is not contaminated because there is hundereds of baby fish in it also.....so i figured it would have alot of nutrients but now that its about a week or 2 into flowering this has been occuring....i planted it a little deeper then i thought....i dont water when it rains and almost every week or 2 times a week we get a little shower BTW.....ill say i buried it to about the first bottom stem literally but it did fine until now....now iits browning from the bottom up about 4 or 5 inches and hasnt gone any further yet...also on the rest of the stalk it looks like it has blended in spots or blothes or whatever you wanna call it but it isnt noticable unless you get about a foot or closer away from the plant....plz i need help this is a beast in need.

looks normal its what my plants do when thay mature thay look like trees