Hi, my name is Matt and am looking to help you (23 years an IT developer and an webmaster, experienced in all four technologies you have stated, was 6+ years Internet Security System Engineer and helped set up first e-banking solution in Slovenia).
Please provide more details to identify the issues. From the description I cannot tell if crashing website is because of:
1. Site load (huge traffic e.g. a lot of visitors or some random daily spikes, can be also because of attacks).
2. Memory issues (lack of memory on a server, not able to handle further app/server requests).
3. Software infinite loop or racing condition (non deterministic algorithm working, causing stalling).
4. Address errors and reverse proxies (non-resolving of requests, overflowing communication interfaces).
5. Security permissions (privileges for changes on the server, can also be a security breach).
Or because of combination of above etc.
While I am not active in such role I'm usually pretty fast to determine main cause of a problem if there is enough logged data to examine (server, communication, application logs etc).
Looking forward to your reply,
Matt