Small changes that cause me problems (or changes that other people consider small, but I consider large):
Any situation where there is either a new person, or a person I was used to has gone.
Situations where people commit to come eg weekly, but only come fortnightly or monthly, and are unpredictable.
New people who do not introduce themselves or are not introduced, and their role is not easily identifiable.
Changes in appointment time, eg a support worker normally comes Tuesday at 10am, but either changes that time or cancels.
Changes in tv schedule. eg when Sky recently took over some extra channels and some shows disappeared and others were rescheduled.
Change of presenter on radio programmes.
When the local shop changes layout or stops selling certain foods.
Menu changes in a cafe or pub.
Staff changes in any shop etc.
If a shop I buy my clothes from goes out of business.
I hate it when they change meds brands from generic to specific, or from normal release to extended. Different pill colours, sizes, shapes etc drive me batty.
Bus schedule changes, and if they change the type of bus used, eg coach to minibus, or the route taken.
My neighbour's routine changes. eg she normally does her garden on Mondays, if she does it another day I get thrown. Fortunately for me she has OCD, so her routine is pretty fixed normally.
I live alone now, but when I lived with other people there were far more problems, eg with things being moved, ppl sitting in my seat, noises, different routines etc etc. Noises at night I find particularly disturbing. If I went to bed before my exhusband, I couldn't sleep. If he did anything like turn on the central heating, or do washing up I would just lie there listening to him. As he had long term effects from a head injury he had insomnia, and I often started work at 7am, so it wasn't an ideal situation.
I'd like to be more 'logical' about this, but its not in my makeup to cope well with these things at the moment.