problem saving settings - what is causing this?

i need some help on my personal website

for some reason which i don't know, i cannot save some admin settings anymore ( i can add nodes / entities and add values though)

but for example when i want to change the textformat of a field, it does not get saved anymore - when i press SAVE and edit the field again, the value is reset to the one before

i checked with the SCHEMA module and it says i have a MISMATCH in the FIELD_SQL_STORAGE on many fields (dont know where this comes from either) its always about being 'not null' => TRUE instead of FALSE

for example:

column field_text_collection_revision_id - difference on: not null
declared: array('description' => 'TODO: please describe this field!', 'type' => 'int', 'not null' => FALSE)
actual: array('description' => 'The field collection item revision id.', 'type' => 'int', 'not null' => TRUE)

might this cause the trouble?

as this is my personal website (i wont get any money from it) i can only pay little money too.

how much? you tell me...

i can give access to the site and phpmyadmin to get things done...