The ill-posed word-search: A sick puzzle

Question

This puzzle started out as ordinary 8-directional word-search puzzle, hiding 19 diseases amongst lots and lots of letters. But then, six letters were infected and became ill, and things became very strange....

In the words-search below, 6 letters have odd properties. Whenever a word 'reaches' one, something happens starting with the next letter. To be clear: There are 6 different affected letters with 6 different effects, and every time a letter is used, the same, letter-specific effect occurs.

Example:
( This is not what is going on in the puzzle! )

Say the letters a & e have become ill. Whenever a is reached in a word, the search direction is shifted one step down, while every time an e is reached, the search direction is shifted one step up. In this case, the word Stackexchange would be found as:



or as:



etc.

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The word-search-puzzle

• There are 19 diseases hidden in the grid

• 6 letters are sick

• the 6 sick letters fill in the colour-boxes in the solution-grid. Arrange them properly, and they will spell the favourite medication prescribed by a specialist. (A very special doctor.)

• The 19 diseases fill in the white/grey spaces in the solution-grid. The grey spaces will spell out the favourite catch-phrase of the same specialist.

To solve the whole puzzle you have to:

• Find all words

• Find the 6 sick letters

• Specify the 6 'illnesses' (=rules) of the special letters

• Completely fill in the solution grid

No partial solutions on this puzzle please!

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Answer 1

Edit 3 - Incorporated complete answer as requested.

The 19 diseases are:

shown in the figures below

The 6 sick letters with their rules are:

c - turn 90 degrees in either direction
e - skip one letter
h - turn 45 degrees to the right
s - skip two letters
t - go up
y - turn the next letter upside-down

The very special doctor is:

the Grim Reaper. His favorite medication was the SCYTHE which is formed from the 6 sick letters.

The favorite catch-phrase is:

Death comes to all of us

The figures:

Answer 2

Okay so I got the "hard part" out of the way over an hour ago, and I was pretty thorough with my steps. I think possibly you used a crossword generator and two were left out? (I found all 5 rules, and there's no phil anywhere (I checked not just near the two capital S as well). I canceled out all of the capital letters pretty thoroughly so I'm relatively certain I found everything but I apologize in advance if I'm mistaken.

Sick letters:

c means turn left 90 degrees, h means turn right 45 degrees, e means skip a letter, s means skip two letters, and t means go up

Phrase:

Death comes to all of us

Word:

The letters were found so the only word it could be (other than techs) would be chest, maybe referring to a medicine chest.

My picture:

I used red to draw the finds, green to cancel out capital letters, and blue to cancel out capital letters that were used in words (I did the rest sequentially without the marker)